Less than 15 minutes into the sci-fi action thriller “Edge of Tomorrow,” Tom Cruise does something unusual. It’s an act he’s only committed on-screen a couple of times in his extensive filmography, specifically, in 2008’s Hitler-assassination drama “Valkyrie” and the hit-man pot boiler “Collateral.”

He dies.

Throughout the first third of “Edge of Tomorrow,” Cruise’s cowardly military officer character — facing off against an overwhelming force of alien invaders and stuck in a time loop a la the Bill Murray comedy “Groundhog Day” – dies again and again, only to reincarnate over and over, until he can figure out how to topple an otherworldly armada bearing down on Earth with overwhelming fire power.

And these are not peaceful deaths. You see Cruise die in gruesome, violent, painful fashion, in ways involving broken bones, concussive pratfalls, bullets to the head and corrosive sprays of alien blood.

“Edge of Tomorrow” director Doug Liman admitted a certain glee in physically annihilating moviedom’s reigning action hero again and again, pointing out that he put his A-list male lead in “Mr. & Mrs. Smith,” the romantic-action-comedy he directed in 2005, through similar paces.

“I enjoyed it as a filmmaker and audiences seem to love it,” Liman said of torturing Cruise. “I loved watching Brad Pitt get the crap beat out of him on ‘Mr. & Mrs. Smith.’ Maybe I take some perverse pleasure in beating up my stars.”

Cruise said he milked one particular death scene for unexpected comedy by recording a blood-curdling scream that was added during post-production.

“You needed a kind of scream where it’s just notdignified,” Cruise said, laughing again. “A kind of scream where, if I screamed like that, it would be like, ‘Oh, really? That’s what I sound like?’”

“I think it set the tone of the film. Death is horrible but it’s also funny,” he said.

Liman, who detailed his process making “Edge of Tomorrow” in a recent Times’ story, marveled at the gung-ho attitude his lead brought to the set for the duration of the film’s grueling three-month shoot at Warner Bros. Studios, Leavesden, a sprawling complex near London.

“I’ve never worked with an actor who worked harder than Tom,” the director said. “Not a movie star, an actor.”

Exhibit A: the challenges Cruise faced putting on and taking off an 85-pound exoskeleton rigged up with all manner of futuristic weaponry that his character wears through his endless D-Day drops into a suicide mission against the forces of extraterrestrial occupied Europe.

“In the beginning, Tom took about 10 minutes to get into his suit,” Liman explained. “He had a stop watch and said, ‘Each time you do this, you’re going to be faster than the time before.’ He had four dressers who would get him in and out of the suit. He got them down to under 30 seconds. It was like a pit crew.”

Unlike most Hollywood leading men who retreat to their trailers in between setups, Cruise opted to hang from a metal scaffolding during breaks in filming.

“Because he’s wearing the suit, they would hook him up to these racks to get the weight off his shoulders,” Liman recalled. “Sometimes, we’d call ‘Cut’ and do the next setup. He’d say, ‘I’m just going to stay in my suit.’ He’s just hanging there in the middle of the set. Everybody hustled twice as fast! The biggest movie star in the world is just hanging like a marionette, waiting for his next take. If I had to go to the bathroom, I would sprint.”

For his part, the star called it all in a day’s work.

“Here’s the thing, I get to do something I love,” Cruise said. “Yes, it’s hard work when you go through it. At the end of the day, you’re tired. It’s not like you’re going to Disneyland. But you’re creating something. As kids, we played in the backyard. At Leavesden, we built the beach at Normandy. You’ve got to have passion for it. It’s fun!”